The present invention relates to an automated method and apparatus for cold-end processing full-lead crystal. More particularly, the invention relates to an automated method and apparatus for grinding and polishing full-lead crystal ornaments, figurines, trophies, and the like.
Cold-end processing of full-lead crystal workpieces such as decorative ornaments, figurines, trophies, or the like (hereinafter xe2x80x9cornamentsxe2x80x9d) is a very labor intensive industry. To make a full-lead crystal ornament, craftsmen first rough cut, carve or grind the ornament from a slab of full-lead crystal. The slabs, when provided from the material manufacturer, typically weigh about 15-60 pounds depending on the specific finished product, and have dull, uneven, unpolished surfaces.
After the ornament is rough cut or carved from the slab, each surface must be ground and polished to a clear, brilliant finish. In the prior art, each surface is first hand ground three times with a progressively finer grinding surface. Each surface is then hand polished three times with a progressively finer polishing surface. This six step grinding/polishing process must be performed on each outer surface of the ornament.
Since the process of cold-end finishing full-lead crystal ornaments is very labor intensive, automation of even a portion of the finishing process would significantly reduce the overall cost of the ornament. It is estimated that the cost of cutting, grinding and polishing the ornament comprises at least about 80 percent of the ornament""s factory cost whereas the cost of the lead-crystal material comprises no more than about 20 percent of the factory cost. Therefore, it would be desirable to reduce the amount of hand labor involved in cold-end finishing full-lead crystal ornaments in order to reduce the overall cost of the ornament.
Some industries teach automated machines for grinding and/or polishing materials having significantly different properties than full-lead crystal. For example, in the marble and granite industry, the Mantello honing machine, Officina Meccanica Antonino Mantello, Catania, Italy, is known for polishing the face surface of large marble or granite workpieces. In the plate glass industry, the Bovone straight line edging machine, Bovone Elettromeccanica, Belforte Monferrato, Italy, is known for edge finishing sheets of plate glass having a material thickness in the range of 2 mm to 25 mm. While the Mantello honing machine and the Bovone edge finishing machine provide a finished surface which is acceptable for marble, granite, and plate glass, respectively, the Mantello honing machine (in its original unmodified condition) cannot provide the clear, brilliant surface finish required for full-lead crystal ornaments and the Bovone straight line edging machine does not have the widthwise capacity to process common full-lead crystal ornaments. Therefore, it would also be desirable to provide an automated apparatus and method capable of providing a finish which is clear and brilliant enough for full-lead crystal, i.e., without visible flaws.
The present invention provides a system of automated apparatus for cutting, beveling, grinding, and polishing, the flat, outer surfaces of full-lead crystal ornaments to a finish which is clear and brillant, and without visible flaws. One apparatus of the system automatically grinds and polishes the large flat face surfaces of a full-lead crystal workpiece. Another apparatus automatically bevels, grinds and polishes the edge surfaces of a full-lead crystal workpiece. Another apparatus automatically cuts intricate shapes in the workpiece.
The face surface finishing apparatus has a housing, a conveyor for carrying the workpiece through the housing, a calibrator, a plurality of grinders, a plurality of polishers, and control means for raising and lowering the calibrator, grinders, and polishers relative to the conveyor and the workpiece supported thereon. The calibrator, grinders and polishers are located above the conveyor belt.
The conveyor preferably includes a horizontal, variable-speed, endless-belt conveyor running lengthwise downline through the housing from the entrance end to the exit end. The conveyor also includes a pair of unpowered, roll conveyors, one located proximate the entrance end and the other located proximate the exit end of the belt-conveyor.
The calibrator is located proximate the entrance end of the housing. The calibrator has a leading, abrasive cutting surface which course grinds the workpiece to a desired thickness. Preferably, the calibrator abrasive cutting surface has a coarseness in the range of about 30 grit to about 50 grit.
The grinders are located downline from the calibrator. Each of the grinders has a motor and a grinding head having an abrasive grinding surface within a range of coarseness, preferably in the range of about 60 grit to about 800 grit. The grinding heads comprise a circular base plate having replaceable grinding pads releasably attached to the base plate. The grinders are arranged sequentially downline within in the housing in an order of decreased coarseness.
The polishers are arranged downline from the grinders within the housing. Each of the polishers has a motor and a polishing head having a coarseness in the perforated pad range. The polishing heads preferably comprise a circular base plate having replaceable polishing pads. The polishing heads are used in conjunction with a polishing compound, preferably cerium oxide.
The control means raises and lowers the calibrator head, grinding heads and polishing heads relative to the conveyor and the unfinished surface of the workpiece supported by the conveyor. The control means also sequentially lowers and raises each of the grinding heads and polishing heads into contact with the workpiece being conveyed downline on the conveyor.
Lubricating fluid nozzles are located around the calibrator head, polishing heads, and grinding heads. The nozzles are connected to a separate sources of lubricating fluid and polishing and direct the flow of fluid onto the unfinished surface of the workpiece during grinding and polishing. A valve controls the flow of fluid through each of the nozzles. A collection basin is located underneath the housing for collecting and recycling the fluid emitted from the nozzles. A dryer is located proximate the exit end of the housing for removing residual fluid from the workpiece.
The edge surface finishing apparatus has a housing, a conveyor for carrying the workpiece through the housing, a plurality of grinders, a plurality of polishers, and control means for raising, lowering and tilting the grinders and polishers relative to the conveyor and the workpiece supported thereon.
The conveyor includes a processing conveyor comprising a pair of opposed, vertically-oriented, variable-speed, endless-belt conveyors running lengthwise downline through the housing from the entrance end to the exit end. The processing grasps or xe2x80x9csandwichesxe2x80x9d the face surfaces of the workpiece and suspends the unfinished edge surface oriented downwardly. The processing conveyor has means for adjusting the distance between the belts to accomodate a variety of workpieces having different thicknesses.
The conveyor also includes horizontal load and unload belt conveyors located in line with the entrance end and the exit end of the processing conveyor. The entrance end load conveyor xe2x80x9cfeedsxe2x80x9d workpieces into the edge surface finishing apparatus. The exit end unload conveyor xe2x80x9cremovesxe2x80x9d workpieces from the edge surface finishing apparatus.
The grinders and polishers are located underneath the vertical belt conveyor. Each of the grinders has a motor and a grinding head having an abrasive grinding surface within a range of coarseness, preferably in the range of about 60 grit to about 800 grit. The grinders are arranged sequentially downline within the housing in an order of decreased coarseness.
The polishers are arranged downline from the grinders within the housing. Each of the polishers has a motor and a polishing head having a coarseness in the felt pad range. The polishing heads preferably comprise a circular base ring having replaceable polishing felt pads. The polishing heads are used in conjunction with a polishing compound, preferably cerium oxide.
The control means raises, lowers and tilts the grinding heads and polishing heads relative to the processing conveyor and the unfinished edge surface of the workpiece supported by the processing conveyor. The control means positions the grinding heads and polishing heads so that each of the heads properly contacts the bottom surface of the workpiece as processed by the preceding head.
Lubricating fluid nozzles are located around each of the polishing heads and grinding heads. The nozzles are connected to separate sources of lubricating fluid and polishing fluid, and direct the flow of fluid onto the unfinished surface of the workpiece during grinding and polishing. A valve controls the flow of fluid through each of the nozzles. A collection basin is located underneath the housing for collecting and recycling the fluid emitted from the nozzles.
The cutting apparatus comprises a high-pressure fluid cutting machine such as an Ingersoll-Rand(copyright) Waterjet cutting machine.
The present invention also provides an automated method of cutting, beveling, grinding, and polishing, full-lead crystal ornaments using one or more of the finishing apparatus described above. An unfinished lead-crystal workpiece is oriented on a conveyor such that a first work surface of the workpiece is unobstructed by and extends outwardly from the conveyor. The workpiece is conveyed over a series of progressively finer grinding heads and polishing heads which are positioned relative to the conveyor and the unfinished work surface of the workpiece. The work surface is simultaneously lubricated with a fluid during grinding and polishing.
After the first work surface is ground and polished, the workpiece is reoriented on the conveyor so that a Liv different unfinished work surface is unobstructed by and extends from the conveyor. The above-described grinding and polishing steps are repeated until each of the desired work surfaces are finished.